BECKHOFF DK9222-1009-0006 - Manual

I/O
Bus Terminal
Application Note DK9222-1009-0006
Keywords
Speed control
Bus Terminals
Energy efficiency
Square characteristic
AC motors
KL2791
Speed control of single-phase AC motors
In order to reduce the power consumption of single-phase AC motors, their speed can be regulated as
required. Depending on the process data, the speed can be reduced in the case of low load requirements in
order to reduce noise emissions, increase energy efficiency and prolong the service life of the units.
Effects of the change in speed
Single-phase AC motors with square load characteristic curves are often used as additional units for fans or pumps, for
example. As opposed to three-phase motors, no start-up optimisation is necessary as in the case of star-delta and adjustment
to different load cases by means of a frequency converter is often not provided for. The additional units are usually switched in
an interval orientated manner or simply activated during a certain phase of the control program. The following AC motors are
in use, depending on the application: capacitor, universal and shaded-pole motors.
M
1~
L1 N
M
1~
L1 N
M
1~
L1 N
Capacitor motor Universal motor Shaded-pole motor
Fig. 1: Controllable AC motors on the KL2791
New Automation Technology Beckhoff 1
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